Effects of Reverberation and Compression on Consonant Identification in Individuals with Hearing Impairment

Abstract

Objectives Hearing aids are frequently used in reverberant environments; however, relatively little is known about how reverberation affects the processing of signals by modern hearing aid algorithms. The purpose of this study was to investigate the acoustic and behavioral effects of reverberation and wide-dynamic range compression (WDRC) in hearing aids on consonant identification for individuals with hearing impairment. Design Twenty-three listeners with mild to moderate sloping sensorineural hearing loss were tested monaurally under varying degrees of reverberation and WDRC conditions. Listeners identified consonants embedded within vowel-consonant-vowel nonsense syllables. Stimuli were processed to simulate a range of realistic reverberation times and WDRC release times using virtual acoustic simulations. Additionally, the effects of these processing conditions were acoustically analyzed using a model of envelope distortion to examine the effects on the temporal envelope. Results Aided consonant identification significantly decreased as reverberation time increased. Consonant identification was also significantly affected by WDRC release time. This relationship was such that individuals tended to perform significantly better with longer release times. There was no significant interaction between reverberation and WDRC. The application of the acoustic model to the processed signal showed a close relationship between trends in the behavioral performance and distortion to the temporal envelope resulting from reverberation and WDRC. The results of the acoustic model demonstrated the same trends found in the behavioral data for both reverberation and WDRC. Conclusions Reverberation and WDRC release time both affect aided consonant identification for individuals with hearing impairment, and these condition effects are associated with alterations to the temporal envelope. There was no significant interaction between reverberation and WDRC release time.

Intelligibility and Clarity of Reverberant Speech: Effects of Wide Dynamic Range Compression Release Time and Working Memory

“…Consistent with Reinhart et al (2016), sentence intelligibility was significantly worse in reverberation; however, unlike Reinhart et al, Shi and Doherty did not find any effect of WDRC release time. The discrepancy between these two studies could be due to several methodological differences in implementing WDRC.…”

“…In a clinical sense, this supports the use of speech perception tests that incorporate realistic reverberation when assessing patient impairment in the real world (e.g., Brungart, Sheffield, & Kubli, 2014;Spitzer, Sandridge, Newman, Sydlowski, & Ghent, 2015). As it pertains to translational research, individuals should be aware as to how reverberation might affect the signal acoustics and how that will affect the generalizability of results in the real world (Bradley, Reich, & Norcross, 1999;Houtgast & Steeneken, 1985;Reinhart et al, 2016).…”

“…The results of Reinhart et al (2016) provide valuable insight into the relationship between reverberation and WDRC release time on a phonemic level. However, nonsense syllables presented without semantic or higher linguistic content also lack real-world validity.…”

“…Thus, working memory may be a point of division among individuals when it comes to determining optimal WDRC release time in reverberant environments. This is especially true given that WDRC release time significantly affects the signal acoustics even in the presence of reverberation (Reinhart et al, 2016). Thus, when examining optimal WDRC release time for reverberant environments in the real world, the role of individual working memory should be considered.…”

“…A recent study by Reinhart, Souza, Srinivasan, and Gallun (2016) investigated the effects of reverberation and WDRC release time on consonant recognition for nonsense syllables in individuals with hearing impairment. It was found that individuals had improved recognition with less reverberation as well as with longer WDRC release times.…”